Hello,My osTicket setup was working perfectly from last 3 months. Suddenly it's not working from yesterday. I haven't uploaded or done anything file or database related changes. I see blank page for both front and SCP urls. So now my support system is totally down.I checked console log in Chrome browser and I found this error:500 Internal Server ErrorI checked error_log file and found this problem:PHP Fatal error: Call to undefined function _S() in /xxxxx/support/include/class.signal.php on line 63Is there any clue how to solve it.My server config:Apache : Apache Phusion_Passenger/4.0.10 mod_bwlimited/1.4 mod_fcgid/2.3.9PHP version : 5.4.41Thanks,Bob